Process of producing light metals by electrolysis.



No.v

E. VON KUGELGEN L G. 0. SBWARD.

PATBNTED APR. 16, w07.'

PROCESS 0F PBODUCING LIGHT METALS BY'ELBCTROLYSIS.

APILIOATION FILED MAY 411905.

WITNESSES:

wenn@ rusas w: wm wasmucw D c.

I l l I i I I l l l INVENTORS:

trolysis of their fused salts.

STATES PATENT OFFICE.

FRANZ VON KGELGEN ANDGEORGE o. sEWARD, OF IIOLOOMBs ROOK, VIRGINIA.

inRoma-se oFPnoDuolNe. LIGHT METALS sv ELEC-moments.

Specication of Letters Patent.'

atent'ed Apri- 16, 1907.

Apunta@ met may 4,1905. serial No. 258,821.

To alt whom it may concern:

Be it known that We, FRANZ lvon KGEL- GEN, a subject of the German Emperor, andl GEORGE O.v SEWARD, a citizen of the United States, both residing at Holcombs Rock, in

'LightMetals by Electrolysis, of which the following is a specification. y

This invention relates to the production of metals of low specific gravity bythe elec- It uhas been'proposed to produce sodium electrolyzing fused sodium chlorid, using 'a molten anode of aheavymetal, as silver or copper,- so that the chlorin liberated at the anode forms a chlorid of the heavy metal.

l The chloridthus formed was expected to remain at the bottom of the electrolyte, be-

cause ot its greater specific'gravity, and thus be kept separate from the sodium, which Was separated at the cathode, which was located at the upper method 4appears at first to operate in accordance with theory, but after a littletime the hea metal is deposited at the cathode instea On account of these difficulties the roce'ss has never beenv pragticed commercial y.

I' Our invention avoids the difficulties heretoore encountered in the effort lto elect-rolyze fused salts of light metals b use of a soluble anode. l By a soluble` anode we mean one which 1s attacked by the clilorin or g negative agents, which would otherwise corother electronegative element' which is liberated at the anode to form a chlorid or other saltof the heavy anode metal.' We have 4found that if such heavy chlorid of the anode metal can be kept Jfrom rising up to or near the cathode the separation of the -heavy metal at the cathode, with its accompanying losses, can be avoided. l

Our invention therefore involves the electrolysis of a haloid or other salt of'a light molten eavy metal i maintaining such conditions as to prevent l use of a` soluble anode beneath of and a cathode above,

metalb thel salt of the heavy metal from circulating upward through the electrolyte far enough to come into contact with the cathode or so nearly adjacent thereto as to be decom osec and :Separate the heavy metal ofzthecat ode. l

part of the electrolyte. This ot sodium, and the output per unit of.V current becomes so low as to be unprotable.

l bottom of the electrolyte.

In the electrolysis of a haloid salt, With a soluble anode ot' heavy metal the'haloid salt of the heavy metal Which is formed" has a specilic gravity sutliciently greater than that of the electrolyte, so that if' undisturbed it would maintain itself in a separate layer betvveen the electrolyte and the molten anode; but it has always been found that in electrolyzing with a current of sufficient density to produce the sodium there .is such disturbance of the heavy salt as to cause it to mixA wi th the lighter salt for-ming 'the electrolyte,

With the result that the heavy salt is decomposed, thus liberating the heavy metal atthe cathode, so that it recombines with the positive element or light metal and eventually stops the production of the latter.

ln practicing our invention we operate unf der different conditions Jfrom those hereto- VJr'ore maintainedavhereby We prevent the contact of the salt ot the anode metal with the cathode. To this end We locate the cathode at the upperpart ofthe electrolyte as remote as practicable from the heavy anode Aand avoid the formation of such currents as will carry the salt ottheanode metal 'up into contact iwith the cathode, removing this salt from time tot-Ime as It forms, so as-to keep X its level as remote as possible from the cathode. We also interpose a diaphragm yof foraminous metal, such as iron-wire cloth, betweenthe cathode and the saltof the an'Ode'meta-l, whereby the latter is confined beneath such diaphragm. The use of such `a metal diaphragm is rendered possible by the absence of free halogen or other electrorode and destroy the metal. The use oi a diaphragm, however, is not under all conditionsindispensable. lt is important to construct the cell oi a sulliciently large diameter in proportion to the current used so that the electrolytic action shall be diffused within' the cell, so as to avoid the formation of energetic currents of liquid which tend to displace and carry up the salt of the heavy anode met-al. "ln addition to these precautions it Is of advantage to provide forthe periodical sett-lingotthe heavy salt beneath the electrolyte, which may be done by discontinuing the electrolytic current at intervals, Whereupon the heavy salt settles quickly to the This -precipitation of the heavy salt instead of being eifected in thev electrolytic cell may be accomlished in a separate settling-vessel by'drawing o flthe electrolyte-eitherintermittently or continuously into a vessel, wherein 4it remains so nearly quiescent as to permit the precipitation of the heavy salt, whereupon the light salt can b'e decanted or drawn off and rel turned to the cell.y

- invention, it 'being understood, how-gever, that various other mechanical arrangements and constructions may be substituted.

Referring to the drawing, let A design-ate an iron pot or vessel having a lining B, of fireclay, magnesia', or other suitable material, and a pool of molten lead C or other heavy metal having l a suitable affinity with the electropositive element to be liberated at the anode, so that it may serve asa soluble anode.

Above this anode floats a bodv of -the molten salt to be electrolyzed D, which in this instance is sodium chlorid, and at the. up-

per part ofthe electrolyte it comes in contact.

with a cathode E, which may be of cast-iron ,1

outer. wall of the cell.

beingshown as annular, forming a part of the and the-cathode is extended in substantiallyv horizontal direction a diaphragm F, which may consist of one or more layers of iron- Wire clothor may be made o'f any suitable generator G and between the negative termaterial; kSuitable electrical connections are made between the vessel A and the positive terminal of a dynamo or other electric minal, thereof and the cathode E. The cell is covered by acover H, of iron, having an A outer ian'ge which is liermeticallysealed, as

by-dippinginto an annular trough I, containing lead which is maintained molten by 'the heat ofthe cell.

jects a feed-pipe J for'introducing Vfresh elec- Through this cover protrolyte, its lower end being sealed in the electrolyte,- This pipe J should be insulated from the cover by apacking of asbestos or othermaterial K. For discharging the 'sodium a tube L leads out from the upper part vof the cell and "discharges into oil in a vessel Mywhereby contact with .the atmos here is avided. `The tube .L requires to` e insu- .lated fromthe vessel A by a packing P, of

asbestos or other material. vA tapfhole Q is provided ,for ischargingthesalt of the anode metal. 'v

l For practicing the process a suitable quanvtit .of

ead is first-placed in the-bottom of thc chlorid to form theelectrolyte is then intro!v duced,preferably in'the molten state, so that Between the anode its heat fuses the lead.A The electrolyte is filled-in to about the level shown, so that it covers the lower part of the annular cathode E. The cover H is applied to exclude air. The current being turned on, electrolytic action takes place, sodium is liberated at the cathode and floats on the electrolyte, as

shown at R, and chlorin isliberated at the anode and attacks ythe lead, forming lead chlorin, which being of greater specific gravity than the electrolyte tends to remain in a separate layer beneath it, as shown at S. The internal currents induced in the electrolyte by the electrolysis tend .to disturb this layer of heavy salt and carry itup through and mix it with the electrolyte- Such liftinv of the lead chlorid or admi'xture thereof witch the electrolyte as should bring a material quantity of it in contact lwith the cathode would defeat the process. This result we prevent by some or all ofthe following expedients: by theiiiterposition of the diaphragm F, Whicl'ifprevents the dissemination of the heavy salt in the upper portion of the electrolyte above the diaphragm and retains the lead chlorid or mixture' of lead chlorid and sodium hierid entirely beneath the diaphragm 5 by'coniining the cathode to the 11pper part of the electrolyte and separatin .it

as far as is practical from the lead anode, t ef cellheing of such dimensions as to make this distance as great as practicable without'pr' y f hibitivelyl increasing the vinternal resistance by tapping off. the lead chlorid at sufficiently frequent intervals in order. to maintain as normal level and the cathode; by avoiding too great a current density, and thereby so4 energetic and localized an electrolytic actionl as to cause too active disturbing currents within the electrolyte, to which end .the cell is made of large diameter for a given amperave, and by precipitating the lead vchlorid out' o the electrolyte Whenever ,its admixture therewith becomes sufficient to disturb. the

roo wide a separation as` practicable between its operation or vseriously diminish the efficiency, M

which is best done by discontinuing the ourrent fora short time to enable the heavy salt to settle, or by' opening the tgp-hole Q the cell may be emptiedof theleaw chlcri d'and sodium chlorid and refilledwith'fi'eshelectrof lyte introduced throug'l'thcpipe J. 'In 'such' 'i case the -chlorids thatare I awnof'may be left in asettling vessel until-the lead chlorid has been precipitated, whereupon thesodium chlorid'may bel drawn off ordecjantedzand used as fresh electrolyte. -""Iffthe^"tw6lsalts arenotfthus 'drawn off, the lead chlorid gradually accumulates asv` the electrolysis proceeds, so that its level rises,andf to keep it as remote as possible from'. the cathode -it is Y drawn o' at interval y Q. Fresh elctrly istjidded *at-intervals', Athrough the pipefiIgJ '.g'YI-,he'ieadcathoderes through the tapholev quires to be repleiisliedoccaeionally.

Our process is useful not only in case of l sodium, but also .in the electrolysisof other lmetallic chlorids. The process ,is generally l. The process 'of ,producing light metals from their salts, which consists 1n electrolyz- I; ing the fuse salt in the presence of a soluble l, anode of heavy metal beneath, and a cathode l above, thereby forming a salt of the heavy l metal overlying the anode, and remote frontl1 the cathode, and preventing circulationof said l, heavy-metal salt upward through the elec- Vtrolyte', whereby to avoid `contactof such salt with the cat-rhode.

rl`he process of )roducing light metals g from their salts, which consists in electrolyzing the fused salts in the presence of a soluble anode of heavy inetal beneath, and a-. cathode above, thereby forming a salt of the heavy metal overlying the anode, and dividing the electrolyte by al diaphragm between' such salt and the cathode whereby to prevent circulation and confine such salt to the lower part of the cell to prevent its reaching the i cathode. l 3. The process-of producing light metals from their salts, which consists in electrolyz- J i l ing the fused salt 1n the presence of a soluble i phragm dividing anode of heavy metal beneath and a cathode above, whereby is formed a salt of the heavy metal, and periodically permitting the precipitationof thev havymetal salt which has become mixed Withthe electrolyte.

4. The 'process of producing light metals from their salts, which consists in electrol zing the fused salt in the presence of a soluble anode of heavy metal beneathI and a cathode above, Whereby'is formed a salt of' the heavy metal, and discontinuing the electrolysisat intervals to permit the precipitation of the heavy-met al salt which has become mixed with the electrolyte.

5. The process of from their salts, which consistsin electrolvz ing the fused salt in the presence of a soluble anode of heavy metal beneath', and a cathode above, thereby forming a salt ofthe heavy Inet-al, and drawing off ,the latter salt periodically to keep its level remote from the cathode.

6. The process of producing light metals fromtheir chlorids, which consists 'in electrolyzing the fused chlorid in presence of a soluble anode of heavy metal beneath, and al cathode above, with a the electrolyte, and periodic allv drawing off horizontal metal dia-- producing light nietals I the salt ofthe heavy anode metal beneath said diaphragm, and adding.

fresh electrolyte above the diaphragm;

ln wit-ness whereof' we have. hereunto signed our naniesin the presence of two sube seribing Witnesses.

FRANZ VON .KUGELGENl GEORGE O. SEWARD. Witnesses: y p J. H. WEBB, C. OFFERHAUS. 

